The formation of protein-protein interfaces is a fundamental step in the functioning of a multitude of biomolecular systems. The assembly of viruses, action of multi-subunit enzymes and recognition of antigen by antibody are only a few of these important systems that rely on the function of specific protein- protein interfaces. The objective of this research is to systematically characterize the nature of protein-protein interfaces for a number of macromolecular assemblies. This work will be carried out by applying computational and interactive computer graphic techniques to a database of known protein structures and their complexes. Analysis and subsequent categorization of prominent patterns of interactions will lead to an ability to functionally dissect protein surfaces and to predict associations (docking) with appropriate function. In addition, a detailed understanding of the nature of quaternary structure formation could lead to insights into the general problem of protein folding. Computational and computer graphic analysis of interfaces will include shape, electrostatic potential and gradient, and mobility characterization. We will examine relative contributions to interfaces from side chains versus main chain, polar versus non-polar and charged versus neutral subtituents. The role of solvent at the interfaces will also be characterized. We plan to examine the spherical plant viruses and the recently available human picorna viruses as a model of assembly systems. We will also look at the well-characterized immunoglobulin fragments and complexes as well as multi-subunit enzymes and transport systems.